Dynamically improving the power factor of PCC using photovoltaic-battery generation system based on hierarchical control strategy

A novel control strategy is proposed to improve the power factor at the point of common coupling (PCC) using the multi-functional photovoltaic (PV)-battery generation system, which can decrease the cost of PV generation, save the investment of excess equipment, and improve the economic efficiency of users and the power supply capacity of the main grid. By considering the rated capacity of the inverter, solar radiation intensity, and simultaneous fluctuations of load power, different operation modes of the PV-battery generation system are analyzed and a hierarchical control strategy is employed. The presented control strategy can achieve the seamless switch from one operation mode to another and guarantee that the PV-inverter can feed active power to the public grid meanwhile provide the reactive power compensation to dynamically improve the power factor of the PCC. A method that makes the remaining PV power save to the battery as much as possible is proposed to improve the utilization of PV and reduce the disposable light, when the grid needs the inverter to output more reactive power not active power but PV can output much aitive power. In low-light condition or at night, the battery discharges to maintain the DC bus voltage, ensuring that the inverter can continue to provide reactive power for the main grid, and the PV is closed automatically without any hardware breaker. A simulation model of the multi-functional PV-battery generation system is built and the results verify the correctness and effectiveness of the proposed control strategy.